Advances in electrophoretic methodology were made on two fronts: i) The mechanism of band spreading and ii) the adaptation of automated apparatus to the separation of subcellular-sized particles. i) The control and predictability of band spreading are important since resolution of bands in electrophoresis, as in other separation methods, depends on it. To date, the mechanisms by which bands spread as a function of migration time or distance have been attributed to the sum of a multitude of factors (diffusion, temperature, field strength, sample load, viscosity, electroendosmosis etc). Our work of this year both in capillary and in gel electrophoresis has fundamentally changed that concept. It was found that under conditions which ruled out everyone of those factors, band spreading was a linear function of migration distance only. Responsible for that increase are the initial band profile and the heterogeneity of the sample with regard to mobility, i.e. surface charge density, size and shape. A mathematical model capable of predicting band spreading on that basis is being devised and will need to be tested. ii) Automated preparative electrophoresis has previously been developed in application to proteins and to gels. Electroelution is conducted into a collection cup descending onto the band of interest under computer control. The recovery is instantly provided by the software, and electroelution may be extended or repeated until recovery of the band is quantitative. We have now extended that procedure to dilute polymer solutions, capable of separating large particles by size, thus eliminating any practical limit with regard to the size of the particle to be isolated. Furthermore, the fluorescent detector of the automated apparatus was used in way that allows for the detection of native, fluorescently unlabeled particles. Ways to increase detection sensitivity of that method, originated last year, were established theoretically and experimentally.